Multifunctional Thin Film Nanofiltration Membrane Incorporated with Reduced Graphene Oxide@TiO2@Ag Nanocomposites for High Desalination Performance, Dye Retention, and Antibacterial Properties.

Abstract

High desalination performance, dyes retention, and antibacterial properties were achieved with a multifunctional thin film nanocomposite (MTFN) membrane, fabricated by the incorporation of a novel nanocomposite structure of reduced graphene oxide@TiO2@Ag (rGO@TiO2@Ag) into the polyamide active layer. The specific characteristics of graphene-based nanocomposite, synthesized by microwave-assisted irradiation process, favored water channelization and provided super-hydrophilicity and antibacterial properties to the MTFN membranes. In comparison with the conventional methods, such as multistep chemical process using strong agents for reduction and long-term energy consuming hydrothermal process, microwave irradiation facilitated a green, fast, and cost-effective route for the fabrication of GO based nanocomposites for multifunctional applications. Interfacial polymerization was performed on a polyethersulfone (PES)/Si3N4 robust hollow fiber substrate using m-phenylenediamine (m-PDA) aqueous solution and 1,3,5-benzenetricarbonyltrichloride (TMC) organic solution. The structural and chemical characteristics of the synthesized nanocomposites and the MTFN membranes were thoroughly studied by a series of characterization analyses (TEM, FE-SEM, XRD, FTIR, EDX, XPS, and AFM). The physicochemical properties and the nanofiltration performance of the MTFN membranes were investigated after incorporation of rGO@TiO2@Ag at various concentrations. The water contact angles confirmed the superb surface hydrophilicity of the MTFN membranes. High permeability (52 L.m-2.h-1), desalination (96% for 1 g/L Na2SO4 feed solution), and dye retention (98% for 0.5 g/L Rose bengal feed solution) were recorded for the MTFN enriched with 0.2 wt% rGO@TiO2@Ag. 90% reduction in the number of viable bacteria (E. coli), after 3 h of contact with MTFN membranes, confirmed the superior antibacterial activity of the produced membranes.